The Department of Psychiatric Demography, which operates the Danish Psychiatric Case Register, has obtained permission to link with other data systems in Denmark, including the Medical Birth Register (all births) and the National Patient Register (all general hospital admissions). This proposal is for analysis of the relationship between pregnancy and birth complications ("PBC's") and hospitalized mental disorder. One goal is to assess the relationship of PBC's to psychiatric history of the mother (40,000 mothers out of 600,000 giving birth). The applicant claims that the ability to study specific complications, related to specific disorders, controlling for variables such as parity, is stronger than in any other study. A second goal is to assess the effect of PBC's on the child's later hospitalization for mental disorder. PBC's are implicated as possible causes of autism, schizophrenia, affective psychosis and other disorders. Many births have passed through the age of risk for autism (448 cases so far), and are entering the age of risk for disorders like schizophrenia (149 so far); affective psychoses (71); other psychoses (753); personality disorders (598); drug and alcohol disorders (213). The applicant claims that this prospective study will have a more representative population base, and more cases, than any other for autism, schizophrenia, and affective psychosis; for other disorders, there are few comparisons. The analysis will assess the effects of specific PBC's and combinations of PBC's, and also the role of PBC's in the relationship of schizophrenia to social class, urban versus rural residence, and season of birth. The specificity of PBC's to different disorders will be assessed, as well as the effect of confounding, suppressing, and interactive variables. The applicant will also estimate population attributable risk for PBC's and all hospitalized mental disorder in Denmark, which may help argue for, and design, prevention trials. Future uses of the Danish Psychiatric Research Database include linkage to create a file of all first degree relatives of individuals with a history of psychiatric hospitalization. This will allow study of the combined effects of genetic and obstetric risk. A later stage might involve examination of birth, medical, and psychiatric records, as well as in-person examinations, for a carefully chosen sample.